rkhunter warning on /dev/shm/mono.*. Is this false positive?

rkhunter is giving warning on /dev/shm/mono.*. I couldn't find anywhere in the web reference to this file related to rkhunter warnings.

[12:38:29]   Checking /dev for suspicious file types         [ Warning ]
[12:38:29] Warning: Suspicious file types found in /dev:
[12:38:29]          /dev/shm/mono.1254: data

Is this a false positive? --- Output of df -h

Filesystem                                 Size  Used Avail Use% Mounted on
udev                                       7.8G     0  7.8G   0% /dev
tmpfs                                      1.6G  2.1M  1.6G   1% /run
/dev/sdb2                                  916G  357G  513G  41% /
tmpfs                                      7.8G  121M  7.7G   2% /dev/shm
tmpfs                                      5.0M  4.0K  5.0M   1% /run/lock
tmpfs                                      7.8G     0  7.8G   0% /sys/fs/cgroup
/dev/sdb1                                  511M  4.5M  507M   1% /boot/efi
/dev/sda1                                  1.8T   87G  1.7T   5% /mnt/HDD_Toshiba
tmpfs                                      1.6G     0  1.6G   0% /run/user/0
SynologyNas.local:/volumeUSB2/usbshare2-1  2.3T  1.6T  683G  71% /mnt/synologyDrive
tmpfs                                      1.6G   20K  1.6G   1% /run/user/121
tmpfs                                      1.6G   48K  1.6G   1% /run/user/1000